Opaque mortgage, buffers, and real EIR

Jesus Thailand mortgages are opaque if you want to really want to understand the figures.

So the banks base your repayments with theoretical interest buffer included, this is somewhat sane idea although its advertised nowhere, note though imo the MMR are probably a high point right now,  it ranges from +0.75% to 1% across the four banks we've tested, and god help you if try to ask the bank staff about this. It's reverse engineering if you can even get an amortization schedule off them.

Once I understood the bank buffer I was getting closer to fully understanding and generating my own amortization schedules thai-style however the example amortization examples have used the advertise EIR+buffer to calculate the monthly interest with the reduce term which is odd (i.e. you should finish your mortgage early if MMR doesnt go up, if it does go up by % of the buffer you finish at the plan term - 360months in our case).   This cake-and-eat-it calc has happened on two banks on two unrelated quotes (i.e not via same broker)

E.g. Let's say a 4.5million mortgage with 4.35% EIR for months 1-36 with a 27500 monthly payment.

I would expect on Month 1 the breakdown to be:

Interest: 16312

Principal: 11187.5